In the removal of asbestos and other particulate contamination, a work area, or containment area, is defined utilizing either the existing walls of a building in combination with plastic sheeting, or by providing walls of plastic sheeting to surround a source of particulate contamination. Entranceways into the containment area are provided, typically through a decontamination chamber connected to the containment area. An air inlet is typically provided to allow air to enter the containment area, preferably through the decontamination chamber.
At least one air moving machine with filtering media therein is located with respect to the containment area to draw high volumes of air into the area. In some cases, the air moving machine is located outside the work area in air flow communication with the work area. The air moving machine draws large volumes of air into the containment area, filters the air, and exhausts the air outside of the work area, or, in some instances, may recirculate air within the containment area. In some cases, several such air moving machines are used to move air into and out of a containment area, depending on the size of the area. Each machine is capable of moving as much as 2,000 CFM of air, the number of air moving machines being sufficient to change the air as often as every 5 minutes.
As described in U.S. Pat. No. 4,604,111, a system and method for removing asbestos is known which minimizes the risk of airborne contamination in a containment area from which asbestos is removed and prevents the escape of contaminated air from the area. This system and method, known as the negative pressure method, provides for defining a containment area that is substantially sealed but has an opening in the area so that relatively large volumes of air can be drawn into the work area by an air moving and filtering unit, which unit filters the air and exhausts the cleansed air outside of the work area.
The air moving and filtering machine, as described in the above-mentioned patent, is capable of drawing relatively high volumes of air into the work area, thereby creating a negative pressure in the work area to prevent any airborne asbestos fibers from leaking outside. By drawing relatively large volumes of air into the work area, the work area is substantially cleansed, thus minimizing workers' risk of exposure to airborne asbestos fibers.
Such an air moving and filtering unit, as described in the aforementioned patent, includes a housing having a blower for drawing air into the housing through an air inlet and filtering the air through filters located therein. After filtering, the air is expelled outwardly from the housing, preferably through a hose arrangement that is associated with a wall of the substantially enclosed containment area, to allow the cleansed air to exit the area. An example of an air moving and filtering unit is manufactured by Microtrap, Inc., of Maple Shade, N.J.
The large amount of air movement created by these air moving and filtering units may present a potential safety hazard in the event of a fire occurring inside or outside the work area. If a fire is within the work area, the air moving machines may fan the fire and accelerate its spread and the intensity of heat and smoke produced. Meanwhile, the smoke caused by the fire may be drawn out of the work area and expelled with great force through the exhaust of the air moving and filtration machine to an area outside the work area. This area may be inside a building within which the enclosure is erected, thereby spreading smoke to different areas of the building.
In the event that a fire is started outside the work area, the air moving and filtering unit may pull smoke and fire into the work area, thus increasing the spread of the fire and smoke.
Various methods and systems for controlling conditions associated with a fire, such as smoke and temperature detection systems, are known. For example, U.S. Pat. No. 4,637,473 describes a fire suppression system for a housing that receives and filters particulate matter. Upon detection of a predetermined temperature difference between the inlet and outlet, a control circuit closes a damper and deactivates a blower motor drawing air through the housing. U.S. Pat. No. 4,363,031 discloses a smoke detection system having a wireless transmitter that sounds a local alarm and transmits signals to other smoke detectors that, in turn, re-transmit the signal and sound local alarms. U.S. Pat. No. 4,659,909 discloses a smoke detector mounted adjacent to an electric kitchen range for detecting smoke and interrupting electrical power to the range.
Similarly, U.S. Pat. No. 3,926,101 describes a smoke detector system for a building that automatically locks certain doors and reverses the direction of fans U.S. Pat. No. 4,063,595 discloses a fire/smoke detector for an air conditioner that, in response to a fire/smoke condition, opens a damper and forces air into the interior of a room to pressurize the room. U.S. Pat. No. 3,826,180 discloses a ventilating fan operable upon activation of a smoke detector. U.S. Pat. No. 4,177,461 discloses a smoke detector for a grain dryer including a transmitter for transmitting an alarm signal to a receiver.
In addition, U.S. Pat. No. 4,391,913 discloses a temperature sensor with a wireless transmitter that transmits signals to a receiver to control the regulation of a radiator system. U.S. Pat. Nos. 4,160,246 and 4,531,114 disclose smoke detectors with wireless transmitters. U.S. Pat. Nos. 4,276,064 and 4,675,203 disclose fire control systems for a paint spray booth and a powder spray booth, respectively.
The above-mentioned prior art fails to disclose any system or method for controlling air moving and filtering units used in conjunction with removal of hazardous particulate matter, such as asbestos.